So far, the improvement of efficiency in a generator has been big problem in the requirement of energy saving. In the structure of the generator, electrical magnet is used for a rotor mainly, which is produced magnetic force by flowing current in a coil installed in the rotor. They know well that the efficiency is improved on the generator by use of a permanent magnet rotor because it is no need to use a current for producing magnetic force. However it has been difficult to use the permanent magnet (PM) generator for such as automotive vehicle because the generated voltage is changed up and down as generator speed change. The reason is that the magnetic force must be reduced to smaller value to maintain constant voltage however the magnetic force dose not change.
However many researchers are making effort to develop the PM generator. Because structure is very simple and generated power is very big in spite of small size due to very strong magnetic force, then PM generators are used for automotive and wind turbine and those have been increasing recently. In the PM generator and motor system, the function of motor can respond to the change of voltage in case of using electric power generated in PM generator, however it is need to control voltage constantly in the case of using electric power for many electric equipments and connecting a storage battery. Many researchers have carried out to research how to control the voltage constantly in PM generator, and the method of controlling the voltage constantly used switching regulator was developed by GM however the system had big problems such as large size of controller, expensive and low efficiency. In order to make the voltage constantly, the electric voltage should be chopped in the switching regulator which is used big size of power transistors, as the result the system was increased in the size, cooling system and cost. On the other hand, the spike of current sometimes produced when the electric power was chopped and the spike pulled the trigger of obstacle in a radio wave then the countermeasure of noise become very difficult problems.
The methods of reducing the magnetic force of permanent magnet when the rotor speed increased were studied by many researchers. For example, the controllers used reactive power were developed, which was needed big size of a converter and a reactor, on the other hand, generators installed coils in the stator in addition to power coil in parallel were developed, which was no need mechanical control systems and the structure was simple because of small number of parts, having reliability and the excellent control-ability of voltage in power coil, they said. In the prior PM generator, it is composed of stator with winding coils, rotor having permanent magnet pieces and control coil supplied current from inverter and the current flowing into the control coil produce magnetic force in optically direction in order to reduce magnetic force to flow into stator and the voltage, which is disclosed in Japanese Patent Application Laid-Open Publication No. 2004-320972.
Furthermore, the generator realized high efficiency was proposed. Prior generator is consisted of stator with winding coil and rotor having permanent magnet pieces and iron cores then controller makes the magnetic force reduce by using reluctance power which is produced the magnetic force on non-symmetrical position disclosed in Japanese Patent Application Laid-Open Publication No. 2003-245000.
Other patent was opened that is consisted rotor installed permanent magnet pieces, stator with coils, and secondary magnetic coils set up in a right angle against the circuit of PM flux to control voltage or current of the power disclosed in Japanese Patent Application Laid-Open Publication No. 2006-529076.
However it is very difficult to weaken magnetic force of permanent magnet in response to increasing rotor speed to the higher by using the methods mentioned above and those technologies have not realized in practical use. On the other hand, DC-DC converter is used for hybrid vehicles, in the system, DC electric power rectified from the generator is chopped by controller and it is transferred to DC power having a constant voltage set in advance furthermore the DC power is changed to AC power by using a inverter. However those were disturbed by complicated and large size of the system to be diffused them in the automotive market. On the other hand, energy problems become worse recently, and about 50% efficiency in the Lundell type generator has not permitted yet in conventional vehicles. As the result, a generator which has simple structure and simple and certain controller is required strongly in the social situation.
The generator with stator wound two kind of coils and one side of coil was used for controlling magnetic force by flowing the current to produce magnetic force in opposed direction were developed by many researcher. In order to reduce the magnetic flux of PM force which flows into stator, the magnetic flux produced by current flowing from an inverter need to be similar shapes to PM flux, however those techniques were very difficult. Furthermore, those electric magnetic flux opposed to PM flux makes the magnetic force of PM material reduce and they suffered with the trouble of generator.
The purpose of the present invention is to solve the problems mentioned above and the generator with complicated structure such as magnetic force control systems is not used and the generator voltage is continuously maintained the voltage set in advance by used small control current and which system dose not affect the magnetic force reduction of permanent magnet then the winding coils are composed power coils having small winding number and control coil with larger winding number than power coil and the power coil connected with control switch, control coil and solenoid coil in series, which switch are located between power coils and control coil and the solenoid coil is not included in the stator, furthermore a controller is connected with control coils and power coils to control the voltage generated in the power coil constantly which is respond by the sensor of voltage installed output terminals and the controller makes the control switch flow small amount of current into control coil.